No, that is not a good analogy at all. It's so poor an analogy that it's challenging to interpret this comment generously. I think you might be arguing facetiously to make a different rhetoric point than the literal content of your post, bot I will respond to your text literally.
Humans have a wide variety of biological variation in metrics we think of as linked to "biological sex" and those metrics are accessibly mutable. Even within the Olympics, the natural variation of these metrics within cis women is a famous topic of debate (Imane Khelif, Caster Semenya, etc.)
Bipedalism is something which varies very rarely and is especially not accessibly mutable.
> Bipedalism is something which varies very rarely and is especially not accessibly mutable.
This would apply to sex chromosomes as well
So? It would apply to sex chromosomes and only sex chromosomes, which is just one observed sex characteristic.
We are talking about sexual dimorphism and secondary sex characteristics.
Humans were understood to be sexually dimorphic before we discovered sex chromosomes in 1905, and we usually label our babies with a biological sex without the aid of consumer genetic testing.